I'm not sure if this is a problem with the World Editor or my own mistake, but I spent all night trying to add a few small lakes to my test map. Every time I save the map and reopen the editor, those lakes (or just a part of them) disappear.

I tried to make some new terrain (by adding it with "insert" to the existing map) and add a few quick lakes and rivers to it, just to find out what's going on. The strange thing is, new terrain also disappeared once, but in next tries it was only water (lakes and rivers), even when they were created in the same time and then saved. Sometimes one lake stay in its place.

I tried to save in other directories and in separate files, but without success. I'm not sure if I'm doing everything right because in all video tutorials water have its surface from the beginning. I must first load the only file with water properties in the list and then apply it to the existing lake or river to make it visible. But after reopening the editor and loading the file water disappears completely - vectors, surface, just like described above.